What rheumatoid factor is
Rheumatoid factor (RF, often written "RA factor") is an antibody found in many — but not all — people with rheumatoid arthritis. It is also positive in:
- Healthy people, especially older adults
- Infections such as hepatitis B and C, tuberculosis and endocarditis
- Other autoimmune conditions — Sjögren's, lupus, mixed connective tissue disease
- Chronic lung and liver disease
A positive RF without joint symptoms usually needs no treatment.
RF and anti-CCP together
| Result | What it suggests |
|---|---|
| RF positive, anti-CCP positive, with swollen joints | Rheumatoid arthritis is very likely — see a rheumatologist promptly |
| RF positive, anti-CCP negative | Less specific — could be RA, another condition, or nothing |
| RF negative, anti-CCP positive | Anti-CCP is more specific for RA; with joint symptoms, take it seriously |
| Both negative, with swollen joints | "Seronegative" RA and other arthritis remain possible — symptoms still matter |
What to do next
- Joint pain with swelling or morning stiffness over 30 minutes? See a rheumatologist — early treatment protects joints.
- No joint symptoms? No treatment needed. Mention it if symptoms appear later.
- The level matters: a high-positive RF (more than three times the upper limit) is more meaningful than a borderline one.
Common questions
Does RA factor positive mean I have rheumatoid arthritis?+
Not by itself. RF is positive in some healthy people and in other conditions. Rheumatoid arthritis is diagnosed from joint symptoms and examination, supported by RF, anti-CCP and inflammation markers.
Can you have rheumatoid arthritis with a negative RA factor?+
Yes. Around a quarter or more of people with RA are RF-negative ("seronegative").
Is anti-CCP better than RF?+
Anti-CCP is more specific for rheumatoid arthritis, so a positive result is more meaningful. The two are often tested together.
Have a result you're worried about?
Bring the report — results only make sense alongside your symptoms and an examination. Walk-in, no appointment needed.
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